Researchers make 'spectacular discovery' of how learning takes place and memories are formed

Jennifer Aniston, Clint Eastwood and Halle Berry images used in ‘mind game’ to establish for the first time how new memories are formed

L-R: Professor Rodrigo Quian Quiroga, director of the Centre for Systems Neuroscience at the University of Leicester and lead author Dr Matias Ison, Lecturer in Bioengineering in the Department of Engineering, University of Leicester

Brain scientists in the UK and US have collaborated to make ‘a spectacular discovery’ - for the first time in human studies - of how memories are formed and new learning takes place.

A collaboration between Dr Matias Ison and Professor Rodrigo Quian Quiroga at the University of Leicester and Dr Itzhak Fried at Ronald Reagan UCLA Medical Center revealed how a neuron in the brain instantly fired differently when a new memory was formed.

The research group at Leicester and UCLA had previously announced the ‘Jennifer Aniston neuron’ – the firing of a single neuron for a single image to form a concept. The team has now proved their hypothesis to be true - and has gone further to demonstrate how new memories are formed.

Clint Eastwood in front of the Leaning Tower of Pisa

The scientists showed patients images of a person in a context e.g. Jennifer Aniston at the Eiffel Tower, Clint Eastwood in front of the Leaning Tower of Pisa, Halle Berry at the Sidney Opera House or Tiger Woods at the White House. They found that the neuron that formerly fired for a single image e.g. Jennifer Aniston or Halle Berry, now also fired for the associated image too i.e. the Eiffel Tower or Sidney Opera House.

Rodrigo Quian Quiroga, head of the Centre for Systems Neuroscience said: “The remarkable result was that the neurons changed their firing properties at the exact moment the subjects formed the new memories - the neuron initially firing to Jennifer Aniston started firing to the Eiffel Tower at the time the subject started remembering this association.

"Moreover, we observed these changes after just a single presentation. This is a radical departure from previous experiments in animals where changes have been observed mainly after long training sessions. This is critical to understanding the neural processes underlying real-life memory formation, as in real life we are not repeatedly exposed to an event in order to remember it - just one exposure is enough.”

Tiger Woods at the White House

Lead author Matias Ison, Lecturer in Bioengineering in the Department of Engineering, said: “This is the first study to look at how a single neuron correlates learning of new contextual associations in the human brain. The single neuron underpinning of memory formation has previously been addressed only by animal studies, which can only offer a limited account of how single events can lead to new episodic memories.”

The discovery that individual neurons in the Medial Temporal Lobe, the brain’s main engine for memory formation, changed their firing to encode new associations even after one single presentation provides a plausible mechanism underlying the creation of new memories. The study suggests that the experience of learning can be traced back to changes in individual neurons in the brain.

The work, which is published in the journal Neuron, is the result of a five year study carried out in collaboration between University of Leicester and Ronald Reagan UCLA Medical Center.